In this paper,we focused on research of optimization conditions to convert colza oil into conjugated linoleic acid by Lactobacillus acidophilus.Through the single factor experiment,we determined the optimal reaction medium,medium concentration,pH,temperature,time and cell concentration.At the same time,the effect of different metal ions on linoleic acid isomerase activity was studied.On this basis,using Box-Benhnken central composite design and response surface method,we optimized and analyzed the technological design which consisted of time,pH,temperature,and cell concentration.When colza oil concentration was 7.5 mg/mL and the amount of lipase was 2mg/30mL,the optimal conversion process was as follows: time 25h,pH 6.5,temperature 36℃,cell concentration 40mg/mL,reaction medium was the 0.1mol/L citric acid-sodium citrate buffer solution.The optimal CLA yield could reach(230.12±7.52)μ g/mL.